komencas repensi miajn decidojn kaj celojn
Is "... devas ne esti..." also acceptable or no?
I think that would make the "ne" apply to both goal and means, which is not what is meant.
I think you would want to arrange it: "Lingvo ne devas esti celo", in which case you'd be articulating that "language doesn't have to be a goal."
Or so say I, the lowly pupil.
How does one say: language has not to be a goal but a means.
eble : « lingvo ne devas esti celo sed rimedo » ?
Could be hard to apply it in Esperanto
The goal is easier communication. The means is a simple language.
Personally, on Duolingo, Esperanto is assuredly my goal. I must be a disappointment to the developers.